This program project, a specialized Cancer Research Center within the Department of Radiation Therapy, Harvard Medical School, supports a variety of basic studies designed to clarify certain aspects of damage interactions between the major therapeutic modalities used in human cancer; radiation, chemotherapeutic agents, and immunologic factors. Interaction between these modalities are studied at the molecular, cellular and tissue levels. Therefore, the major purpose of this Center will be to provide a focus for multi-disciplinary research directed to the improved management of human cancer and to establish opportunities for research collaboration between individuals whose major interest is oncologic medicine. Provision is made for sufficient fiscal flexibility to insure efficient expansion into research and clinical activities as these become appropriate. The Center is organized in a way to provide continued review and evaluation of all Center activities. The research activities of the Center will be based in the Joint Center for Radiation Therapy, Department of Radiation Therapy. However, a portion of the research is housed in the Charles A. Dana Center of the Sidney Farber Cancer Center and provides an opportunity for close collaboration between investigators in radiation effects and those in medical oncology.